Thermal ink jet printing has been described in many technical publications, and one such publication relevant to this invention is the Hewlett Packard Journal, Volume 36, Number 5, May 1985, incorporated herein by reference.
In the art of thermal ink jet printing, it is known to provide ball and stitch wire bonding to a thermal ink jet thin film resistor substrate in order to complete electrical signal paths to the individual resistive heater elements on the substrate. Whereas these wire bonding techniques have proven generally satisfactory in many respects, they impose a limiting factor upon the reduction in substrate size used for housing a give number of resistive heater elements. Since the cost of the substrate, especially in the case of monocrystalline silicon, represents a significant percentage of the overall cost of the thermal ink jet print head, then the desirability of even further reducing the substrate size is manifest.
In addition to imposing a limitation on the reduction in substrate size, the ball and stitch wire bonding process of the prior art also imposed a limitation on the achievable packing density of the complete print head assembly.